Lean Horse Ultra Marathon
Trail in United States, Custer
About
A multi-distance ultra hosted in and around Custer, South Dakota, following the Mickelson Trail with iconic Black Hills scenery. The event includes 100 Mile, 50 Mile, 30 Mile, and 20 Mile options, plus a 30 Mile Black Hills CrossFit Edition.
Catering & aid stations
Aid stations are spaced 5–8 miles apart along the route, with on-course food and drink provided at each station.
Pacers
Pacers are allowed on the 100 mile race for the final 50 miles; multiple pacers may be used, but only one at a time, and they can be exchanged at any aid station. Pacers are not permitted on the 50, 30, or 20 mile events.
Results
View official resultsTypical weather in Custer
Monthly averages based on historical data (2000–present).
Route maps
What's included in entry
- Race Number
- Bib
- Chip Timing
- Race T-shirt
- On-course catering/aid stations
FAQ
Can I have a Pacer?
Pacers are allowed only on the 100 mile race for the final 50 miles; one pacer at a time, with exchanges permitted at any aid station. Pacers are not allowed on 50, 30, or 20 mile events.
Can I have Crew members at the aid stations?
Yes — crew members may cheer and assist at any aid station.
Do you recommend Trekking Poles?
Some runners use them. The course is crushed limestone and fairly smooth; most do not use poles, but if you usually rely on them it’s a good idea to bring them.
Do you recommend Gaiters?
About 10% of runners use gaiters.
I’m injured and can’t run — can I get a refund?
Refunds are not offered, but you may defer your registration for up to two years. Contact us if you cannot attend this year and again when ready to register next year.
How far apart are the Aid Stations?
Aid stations are spaced 5 to 8 miles apart. See the course information page for cutoff details.
How long do I have to finish the race?
100 mile: 32 hours; 50 mile: 15 hours; 30 and 20 mile events: 12 hours. All events finish at 8:00 PM Saturday evening.
Is there a cap on entries?
Yes: 100 milers = 125 entries; 50 milers = 100 entries; 30 milers = 100 entries; 20 milers = 100 entries. Black Hills CrossFit Edition: 40 Singles, 40 Teams of 3, 20 Teams of 6.
Last updated: Jun 6, 2026, 12:15:43 AM
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